The present invention relates generally to bar code label detection and decoding. More particularly, the invention relates to improved methods and apparatus for detecting the presence of a supplemental bar code label to be read in conjunction with a primary bar code label and representing information supplementing the information represented by the primary bar code label.
Bar codes are widely used to provide fast and convenient identification of an item. Affixing a bar code to an item provides a machine-readable label, which may contain direct information about the item, or may serve as an index to a stored catalog or directory of items, which may contain as much information about each item as is desired. The use of bar codes is particularly prevalent in retailing. A specific brand or model of an item can be uniquely identified using a bar-coded identification number, with the identification number being quickly and easily read at the time of a transaction. Because the specific class of item can be identified, it is not necessary to place pricing information on the item. Instead, pricing information can be stored in a central computer, making it easy to change pricing for a particular brand or model without individually marking each item. Moreover, the identifying information contained in a bar code makes it easy to maintain records of inventory and to track and store sales information for an item.
It is often desirable to include supplemental information about particular items in a class of items, which are distinguished in some way from the class as a whole. For example, in the case of perishable foods, it is often desirable to discount an individual item, which is approaching the end of its shelf life without discounting similar items, which are not approaching the end of their shelf lives. One advantageous approach for distinguishing between bar coded products is to attach a supplemental bar code label to selected products. The supplemental label is read in conjunction with a standard, or primary, bar code label by a suitably adapted scanner. After a successful read of the primary label, the scanner seeks a supplemental label such as a special markdown label placed in the vicinity of the product identification label and preferably placed so as to partially obscure the primary label. If a supplemental label is detected, the transaction is conducted in accordance with the additional information contained in the supplemental label. Details of the use and processing of supplemental bar code labels are described in Blanford U.S. Pat. No. 6,158,660, assigned to the assignee of the present invention and incorporated herein by reference in its entirety.
Typically, a standard bar code has no features indicating whether or not a supplemental label is present. Therefore, adding a supplemental label can be accomplished without requiring changes to or removal of an existing primary label. However, because the primary label does not indicate whether or not a supplemental label is present, the scanner must search for and detect the supplemental label without the assistance, which would be available, if the primary label contained such an indication. Once a primary label has been scanned, the possibility exists that a complete scan of the product has been accomplished and no supplemental label exists to be scanned. If a supplemental label exists but is not struck by a scan line, the scanner will fail to detect the supplemental label and will simply process the primary label as if it were not accompanied by a supplemental label. This problem is exacerbated by the fact that some supplemental labels are not designed to be omnidirectionally scanned and are particularly difficult to detect.
It is possible to increase the likelihood of detecting a supplemental label by increasing the time allowed to search for a supplemental label after the primary label is detected. However, simply increasing the search time in all cases decreases efficiency, because time will be wasted in many cases by spending this increased time to search for a supplemental label when none exists. There exists, therefore, a need for a scanner which increases the likelihood of detecting a supplemental label but does not decrease efficiency by extending a search for a supplemental label whether or not a supplemental label is likely to exist.
According to one aspect, an improved scanner according to the present invention determines when a supplemental label is likely to be present by tracking past experience. If a scan has occurred in which a particular primary label has been detected in conjunction with a supplemental label, the scanner stores this experience and similar experiences, in order to identify a primary label or labels which are likely to be accompanied by supplemental label. Each bar code appearing on a primary bar code label is stored in a database along with a value reflecting the expected probability that the primary label bearing the bar code will be accompanied by a supplemental label. If a primary bar code label is subsequently detected in a scan and a supplemental bar code label is not immediately detected, the scanner searches the database for the bar code and retrieves the value associated with the bar code. Depending on the value associated with the bar code, the scanner may refrain from searching for a supplemental label, may conduct a standard default search for a supplemental label, may conduct a search based on the retrieved value or may conduct an indefinite search for a supplemental label until one is found or until the operator intervenes to force an end to the search. Alternatively, a central database of primary bar code labels may be maintained at a retail location or elsewhere and downloaded to each of a plurality of scanners operating at the retail location. Such a database may be built from ongoing scanning experience of each of the scanners, or alternatively may be constructed from known information about which bar codes will be accompanied by supplemental labels codes and the likelihood for each bar code that it will be accompanied by a supplemental label.
A more complete understanding of the present invention, as well as further features and advantages of the invention, will be apparent from the following Detailed Description and the accompanying drawings.